Chemistry notes (from specification)

4 Subject Content

• The specification is structured in two columns:

  • Left Column: Contains the assessed specification content.

  • Right Column: Provides opportunities for skills development related to working scientifically, mathematical requirements, and apparatus techniques.

• Skills reference:

  • WS: Working Scientifically (Page 11)

  • MS: Mathematical Requirements (Page 99)

  • AT: Use of Apparatus and Techniques (Page 101)

• Each topic starts with an overview providing broader context for teaching and learning, though not directly assessed.

• Assessable content is replicated in the left column.

• Content co-teachable with GCSE Combined Science: Trilogy.

• Chemistry-only content is marked in the specification with (chemistry only).

• Higher Tier content is indicated with (HT only).

• It is encouraged to integrate mathematical skills across the course, even if only assessed in specific areas noted in the Mathematical Requirements section.

4.1 Atomic Structure and the Periodic Table

• The Periodic Table is a tool for organizing known chemical elements based on their physical and chemical properties.

• The history of the periodic table and atomic models illustrates the evolution of scientific understanding based on new evidence.

• Elements' arrangement in the modern periodic table reflects atomic structure, supporting the nuclear atom model with electrons in energy levels.

4.1.1 A Simple Model of the Atom, Symbols, and Isotopes

4.1.1.1 Atoms, Elements, and Compounds

• Atoms are the smallest units of elements that exist; represented by chemical symbols (e.g., O for oxygen, Na for sodium).

• About 100 elements exist, listed in the periodic table.

• Compounds form when elements chemically react and combine in fixed ratios through chemical reactions, which always produce new substances and involve energy changes.

• Compounds can only be separated into individual elements through chemical reactions.

• Students should learn:

  • Use of the first 20 elements' names and symbols from the periodic table, particularly Groups 1 and 7.

  • Ability to identify compounds from given formulas and write word equations from specified reactions, including balanced equations.

4.1.1.2 Mixtures

• Mixtures are composed of different elements or compounds not chemically bonded, maintaining their individual properties.

• Separation methods include filtration, crystallization, distillation, and chromatography.

• Students should:

  • Describe and exemplify separation processes.

  • Suggest appropriate techniques for separating mixtures.

4.1.1.3 Development of the Model of the Atom

• Scientific understanding evolves with new evidence.

• Early atomic models (plum pudding model) were revised after the discovery of the electron, leading to the nuclear model.

• Key figures include:

  • Niels Bohr: suggested electron orbits.

  • James Chadwick: proposed neutrons in the nucleus.

• Students should:

  • Describe historical contexts of the atomic model development.

  • Distinguish between the plum pudding model and nuclear model.

4.1.1.4 Relative Electrical Charges of Subatomic Particles

• Subatomic Particle Charges:

  • Neutrons: 0 charge

  • Protons: +1 charge

  • Electrons: -1 charge

• Overall, atoms are neutral due to equal numbers of protons and electrons.

4.1.1.5 Size and Mass of Atoms

• Atoms are about 0.1 nm in radius. Their nuclei are even smaller (about 1/10,000 of the atom's size).

• Mass number equals protons + neutrons. Isotopes are atoms of the same element with varying neutrons.

4.1.1.6 Relative Atomic Mass

• Relative atomic mass is an average reflecting isotope abundance.

4.1.1.7 Electronic Structure

• Electrons occupy the lowest available energy levels (or shells).

• Example: Sodium's electronic structure is 2,8,1.

4.1.2 The Periodic Table

4.1.2.1 The Periodic Table Structure

• Arranged by increasing atomic number; similar properties are grouped.

• Elements have the same outer shell electrons in the same group, hence similar properties.

4.1.2.2 Development of the Periodic Table

• Early tables based on atomic weights were incomplete; Mendeleev addressed gaps and incorrect placements.

4.1.2.3 Metals and Non-Metals

• Metals lose electrons to form positive ions; non-metals do not.

• Majority of elements are metals, mainly in the left and bottom periodic table.

4.1.2.4 Group 0: Noble Gases

• Unreactive due to full outer electron shells (except Helium).

4.1.2.5 Group 1: Alkali Metals

• Characterized by one outer shell electron; highly reactive; reactivity increases down the group.

4.1.2.6 Group 7: Halogens

• Reactive non-metals with seven outer shell electrons; reactivity decreases down the group.

4.1.3 Properties of Transition Metals (chemistry only)

4.1.3.1 Comparison with Group 1 Elements

• Transition metals differ from Group 1 in properties like melting points and reactivity.

4.2 Bonding, Structure, and Properties of Matter

4.2.1 Chemical Bonds

• Types include ionic, covalent, and metallic.

4.2.2 How Bonding and Structure are Related to Substance Properties

States of Matter:

• Solid, liquid, gas interpretations.

• Factors affecting state include temperature and forces between particles.